Clean-burning fuels, aftertreatment and other innovations place the heavy-duty internal combustion engine (ICE) on a low-carbon emissions trajectory.
Agriculture, industrial, mining, construction, freight transport and other major global economy sectors rely on vehicle power to thrive. “Internal combustion engines – those powered by gasoline, diesel, natural gas or propane – really are key to our current economy, and we see [the ICE] as a key part of our energy future,” Allen Schaeffer, executive director of the Engine Technology Forum, a U.S.-based educational organization, said during a September webinar.
Hosted by the Engine Technology Forum, the “Taking Internal Combustion Engines to the Next Level” session focused on current and under-development innovations aimed at increasing engine efficiency and lowering emissions.
Bio-fueling ICE
“With biodiesel, it’s a very sustainable industry for food and fuel,” said Steve Howell, founding partner of Marc-IV (M4) Consulting and chair of the American Society of Testing and Materials Biodiesel Task Force. Biomass-based diesel fuels can be made from animal fats or various oils, including soybean oil and distillers’ corn oil.
Production of biodiesel and renewable diesel has risen dramatically over the past 15 years. In 2010, fuel production reached 200 million gallons and soared to more than 4.5 billion gallons in 2023. “We’re right around 50/50 renewable diesel and biodiesel in North America today,” Howell said. The long-term projection is 6 billion gallons by 2030 and 15 billion gallons by 2050. Feedstock capacity can support an additional 1.8 billion gallons of biomass-based diesel production through 2025, according to industry research.
Using low-carbon biomass diesel in internal combustion engines could reduce atmospheric carbon by 70%, according to Howell. “The industry is doing the work. So B100 [pure, unblended biodiesel], RD100 [renewable diesel] or a blend of the two will be viable options for low net-carbon combustion in 2030, 2050 and beyond,” Howell said.
Diesel-fuel sulfur content in the U.S. market is 15 ppm maximum, although certain off-road applications can use a higher sulfur diesel. Mary Dery, Innospec’s Performance Additives technical director, pointed out that untreated diesel fuel can create engine performance issues. For example, if a fuel injector is dispensing a direct stream versus an aerosol spray, that’s problematic. “It means the fuel is not going to combust properly in the combustion chamber, which leads to poor fuel economy. And it ends up making more particulates,” Dery said, adding a fuel detergent can resolve the issue.
Dery cited several field-trial examples to illustrate how a diesel fuel additive can improve engine performance. In a field test involving a John Deere 5100E farm tractor with 1,800-plus hours of operation, the vehicle’s untreated fuel injector was removed, revealing deep caverns of deposits.
“It looked like a volcano. But after only 100 hours of operating on a detergent additive in the fuel, the deposits around the [fuel injector] holes eroded away, and the NOx emissions were reduced by 30 percent,” Dery said. She also noted that there was a 34% reduction in 2.5 PM particulate emissions and a 30% reduction in soot emissions.
Engine Makeovers
FPT Industrial engineers designed a new heavy-duty engine that makes gains in performance and braking power while lowering fuel consumption and weight when compared to its predecessor. The XCursor 13 (XC13), which is FPT’s first single-base multi-fuel engine, also meets 2025 European Union CO2 reduction targets for heavy-duty trucks. “It’s easily the most exciting time within our industry since its inception,” said Ivan Tate, technical center director for FPT Industrial, headquartered in Turin, Italy.
The new 13-L inline 6-cylinder XC13 has compacted graphite iron castings for the cylinder block and cylinder heads. “This enables us to be lighter but also more rigid,” Tate said, adding that the materials change also helps with emissions and the amount of cylinder pressure that can be maintained. Friction reduction resulted from using new materials for the connecting rod pins and crankpins. Other changes include a new valve train system, using a variable oil and water pump, and employing advanced combustion control and thermal management.
In its diesel configuration, the XC13 – compared to the predecessor C13 – gains 2% more power and 12% more torque, achieves up to 7% lower fuel consumption, reduces weight by 10% and nets a 29% improvement in braking power. XC13’s natural gas version gains 9% power and 10% torque, consumes up to 8% less fuel, cuts weight by 10% and improves braking power by 300%, compared to its C13 predecessor.
“One of our biggest requirements was to increase the braking power of the engine brake,” Tate said. The diesel version of the XC13 engine provides up to 600 hp (442 kW) and 2,100 lb-ft (2,850 Nm), while the natural gas variant offers up to 520 hp (382 kW) and 1,840 lb-ft (2,500 Nm).
Stanadyne, Katech Engineering and the Propane Education & Research Council’s (PERC) involvement in a liquid propane gas (LPG) engine project culminated in 2023 with testing of the novel LPG components/systems on a GM L8T engine. (Baseline engine is a direct-injection, gasoline-fueled, 6.6-L V8 designed for medium- and heavy-duty pickup trucks.)
A vapor lock inhibiting system – with hardware and software strategies designed and developed by Katech – ensures LPG delivery to a Stanadyne-developed LPG direct-injection fuel pump (which features a unique liquid flow path design) and injector system (including additional coatings on the fuel injectors for greater wear resistance). Testing confirmed that the LPG system can deliver propane fuel at a constant 350-bar pressure directly into the engine while mitigating the potential for vapor lock.
A 250-hour performance and durability test – completed on the firing engine – included test cycles for heat soak, hot shutdown, refueling, and on/off-road applicable load points. During testing, the LPG direct-injection system matched or exceeded the power and torque performance of the baselined direct-injection gasoline engine.
LPG typically offers an approximate 5 to 10% reduction in carbon dioxide emissions when compared to traditional diesel fuel. “There is a potential to leverage rDME (renewable dimethyl ether) blends and renewable propane with this new technology to achieve net-zero carbon emissions,” said Srinu Gunturu, Stanadyne’s chief engineer. Technology is ready for the commercialization of LPG direct-injection engines, according to Gunturu.
Emission Controls
Three-way catalysts have been in the marketplace since the 1970s and the technology has evolved over the decades. “We need catalysts that can work at low temperature ranges as well as be durable in high temperatures. This is really an ongoing challenge – in a good way – for us in our catalyst development,” said Louise Arnold, product line manager for Johnson Matthey, a 207-year-old company with 50-plus years of emissions control expertise.
A next-generation three-way catalyst from Johnson Matthey achieves a faster light-off for improved emissions performance and a 30% cost reduction for PGM (platinum group metals). Arnold also noted that particulate filter applications for gasoline engines are revving up. “This is established technology for the European and China markets, so it’s exciting for us to start seeing this application in North America,” Arnold said.
Nick Morley, Tenneco’s engineering director for controls and advanced technology, gave a snapshot overview of three emissions-reduction technologies: a fuel burner, an electric heater, and a dual dosing and advanced mixing system. The fuel burner rapidly heats the aftertreatment to maximize efficiency, enabling the engine to transition to fuel-economy mode sooner. In one example, a six-minute improvement was achieved on a diesel engine commercial truck fitted with a fuel burner.
“It does depend on the test cycle, but you can have CO2 neutrality with a nearly 90% improvement in NOx with a [fuel] burner,” Morley said.
For vehicles with a 48-volt battery architecture, an electric heater is an option “that’s a simpler integration versus a fuel burner,” according to Morley. For a plug-in hybrid vehicle, an electric heater can have a near-zero impact on fuel economy, and multiple heaters can be used if needed.
A dual-dosing SCR (selective catalytic reduction) system, another option for diesel engines, essentially brings the SCR closer to the engine, taking advantage of the available heat. The technology offers packaging flexibility and provides NO2/NOx ratio controls for passive regeneration.
“There certainly are a lot of proven technologies – not only in the aftertreatment space but also in the fuels and engine realm – that can allow us to meet our emissions targets both today and tomorrow,” Morley said.
Originally shared by SAE International, October 3, 2024. Title updated for clarity and purpose.